/**
 * This jQuery plugin displays pagination links inside the selected elements.
 * 
 * This plugin needs at least jQuery 1.4.2
 *
 * @author Gabriel Birke (birke *at* d-scribe *dot* de)
 * @version 2.2
 * @param {int} maxentries Number of entries to paginate
 * @param {Object} opts Several options (see README for documentation)
 * @return {Object} jQuery Object
 */

define(function () {
    return function (jQuery) {
    	var $=jQuery;
		 (function($){
			/**
			 * @class Class for calculating pagination values
			 */
			$.PaginationCalculator = function(maxentries, opts) {
				this.maxentries = maxentries;
				this.opts = opts;
			};
			
			$.extend($.PaginationCalculator.prototype, {
				/**
				 * Calculate the maximum number of pages
				 * @method
				 * @returns {Number}
				 */
				numPages:function() {
					return Math.ceil(this.maxentries/this.opts.items_per_page);
				},
				/**
				 * Calculate start and end point of pagination links depending on 
				 * current_page and num_display_entries.
				 * @returns {Array}
				 */
				getInterval:function(current_page)  {
					var ne_half = Math.floor(this.opts.num_display_entries/2);
					var np = this.numPages();
					var upper_limit = np - this.opts.num_display_entries;
					var start = current_page > ne_half ? Math.max( Math.min(current_page - ne_half, upper_limit), 0 ) : 0;
					var end = current_page > ne_half?Math.min(current_page+ne_half + (this.opts.num_display_entries % 2), np):Math.min(this.opts.num_display_entries, np);
					return {start:start, end:end};
				}
			});
			
			// Initialize jQuery object container for pagination renderers
			$.PaginationRenderers = {};
			
			/**
			 * @class Default renderer for rendering pagination links
			 */
			$.PaginationRenderers.defaultRenderer = function(maxentries, opts) {
				this.maxentries = maxentries;
				this.opts = opts;
				this.pc = new $.PaginationCalculator(maxentries, opts);
			};
			$.extend($.PaginationRenderers.defaultRenderer.prototype, {
				/**
				 * Helper function for generating a single link (or a span tag if it's the current page)
				 * @param {Number} page_id The page id for the new item
				 * @param {Number} current_page 
				 * @param {Object} appendopts Options for the new item: text and classes
				 * @returns {jQuery} jQuery object containing the link
				 */
				createLink:function(page_id, current_page, appendopts){
					var lnk, np = this.pc.numPages();
					page_id = page_id<0?0:(page_id<np?page_id:np-1); // Normalize page id to sane value
					appendopts = $.extend({text:page_id+1, classes:""}, appendopts||{});
					if(page_id == current_page){
						lnk = $("<span class='current'>" + appendopts.text + "</span>");
					}
					else
					{
						lnk = $("<a>" + appendopts.text + "</a>")
							.attr('href', this.opts.link_to.replace(/__id__/,page_id));
					}
					if(appendopts.classes){ lnk.addClass(appendopts.classes); }
					if(appendopts.rel){ lnk.attr('rel', appendopts.rel); }
					lnk.data('page_id', page_id);
					return lnk;
				},
				// Generate a range of numeric links 
				appendRange:function(container, current_page, start, end, opts) {
					var i;
					for(i=start; i<end; i++) {
						this.createLink(i, current_page, opts).appendTo(container);
					}
				},
				getLinks:function(current_page, eventHandler) {
					var begin, end,
						interval = this.pc.getInterval(current_page),
						np = this.pc.numPages(),
						fragment = $("<div class='pagination'></div>");
					
					// Generate "Previous"-Link
					if(this.opts.prev_text && (current_page > 0 || this.opts.prev_show_always)){
						fragment.append(this.createLink(current_page-1, current_page, {text:this.opts.prev_text, classes:"prev",rel:"prev"}));
					}
					// Generate starting points
					if (interval.start > 0 && this.opts.num_edge_entries > 0)
					{
						end = Math.min(this.opts.num_edge_entries, interval.start);
						this.appendRange(fragment, current_page, 0, end, {classes:'sp'});
						if(this.opts.num_edge_entries < interval.start && this.opts.ellipse_text)
						{
							$("<span>"+this.opts.ellipse_text+"</span>").appendTo(fragment);
						}
					}
					// Generate interval links
					this.appendRange(fragment, current_page, interval.start, interval.end);
					// Generate ending points
					if (interval.end < np && this.opts.num_edge_entries > 0)
					{
						if(np-this.opts.num_edge_entries > interval.end && this.opts.ellipse_text)
						{
							$("<span>"+this.opts.ellipse_text+"</span>").appendTo(fragment);
						}
						begin = Math.max(np-this.opts.num_edge_entries, interval.end);
						this.appendRange(fragment, current_page, begin, np, {classes:'ep'});
						
					}
					// Generate "Next"-Link
					if(this.opts.next_text && (current_page < np-1 || this.opts.next_show_always)){
						fragment.append(this.createLink(current_page+1, current_page, {text:this.opts.next_text, classes:"next",rel:"next"}));
					}
					$('a', fragment).click(eventHandler);
					return fragment;
				}
			});
			
			// Extend jQuery
			$.fn.pagination = function(maxentries, opts){
				
				// Initialize options with default values
				opts = $.extend({
					items_per_page:10,
					num_display_entries:11,
					current_page:0,
					num_edge_entries:0,
					link_to:"#",
					prev_text:"Prev",
					next_text:"Next",
					ellipse_text:"...",
					prev_show_always:true,
					next_show_always:true,
					renderer:"defaultRenderer",
					show_if_single_page:false,
					load_first_page:true,
					callback:function(){return false;}
				},opts||{});
				
				var containers = this,
					renderer, links, current_page;
				
				/**
				 * This is the event handling function for the pagination links. 
				 * @param {int} page_id The new page number
				 */
				function paginationClickHandler(evt){
					var links, 
						new_current_page = $(evt.target).data('page_id'),
						continuePropagation = selectPage(new_current_page);
					if (!continuePropagation) {
						evt.stopPropagation();
					}
					return continuePropagation;
				}
				
				/**
				 * This is a utility function for the internal event handlers. 
				 * It sets the new current page on the pagination container objects, 
				 * generates a new HTMl fragment for the pagination links and calls
				 * the callback function.
				 */
				function selectPage(new_current_page) {
					// update the link display of a all containers
					containers.data('current_page', new_current_page);
					links = renderer.getLinks(new_current_page, paginationClickHandler);
					containers.empty();
					links.appendTo(containers);
					// call the callback and propagate the event if it does not return false
					var continuePropagation = opts.callback(new_current_page, containers);
					return continuePropagation;
				}
				
				// -----------------------------------
				// Initialize containers
				// -----------------------------------
				current_page = parseInt(opts.current_page, 10);
				containers.data('current_page', current_page);
				// Create a sane value for maxentries and items_per_page
				maxentries = (!maxentries || maxentries < 0)?1:maxentries;
				opts.items_per_page = (!opts.items_per_page || opts.items_per_page < 0)?1:opts.items_per_page;
				
				if(!$.PaginationRenderers[opts.renderer])
				{
					throw new ReferenceError("Pagination renderer '" + opts.renderer + "' was not found in jQuery.PaginationRenderers object.");
				}
				renderer = new $.PaginationRenderers[opts.renderer](maxentries, opts);
				
				// Attach control events to the DOM elements
				var pc = new $.PaginationCalculator(maxentries, opts);
				var np = pc.numPages();
				containers.off('setPage').on('setPage', {numPages:np}, function(evt, page_id) { 
						if(page_id >= 0 && page_id < evt.data.numPages) {
							selectPage(page_id); return false;
						}
				});
				containers.off('prevPage').on('prevPage', function(evt){
						var current_page = $(this).data('current_page');
						if (current_page > 0) {
							selectPage(current_page - 1);
						}
						return false;
				});
				containers.off('nextPage').on('nextPage', {numPages:np}, function(evt){
						var current_page = $(this).data('current_page');
						if(current_page < evt.data.numPages - 1) {
							selectPage(current_page + 1);
						}
						return false;
				});
				containers.off('currentPage').on('currentPage', function(){
						var current_page = $(this).data('current_page');
						selectPage(current_page);
						return false;
				});
				
				// When all initialisation is done, draw the links
				links = renderer.getLinks(current_page, paginationClickHandler);
				containers.empty();
				if(np > 1 || opts.show_if_single_page) {
					links.appendTo(containers);
				}
				// call callback function
				if(opts.load_first_page) {
					opts.callback(current_page, containers);
				}
			}; // End of $.fn.pagination block
			
		})(jQuery);
    }
});